JP2014142205A - Stroke sensor, and actuator and rear wheel steering apparatus including the stroke sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stroke sensor capable of suppressing a large difference between a detected stroke position and an actual stroke position, and an actuator and a rear wheel steering apparatus including the stroke sensor.SOLUTION: A stroke sensor 63 includes a bridge circuit configured by first and second resistors 81, 82 connected to ground terminals 86, 88 becoming ground potential, a common resistor 83 connected to a power supply terminal 90 becoming high potential, a first contact body 91 brought into contact with the first resistor 81 and the common resistor 83, and a second contact body 92 brought into contact with the second resistor 82 and the common resistor 83. The first contact body 91 and the second contact body 92 are coupled with each other by a coupling member 93 so as to be reciprocated in accompany with a movable iron core while keeping an interval in a stroke direction at a predetermined interval. When the other voltage value is not changed even when either one voltage value generated in voltage values of the first and second contact bodies 91, 92 is changed, an ECU 71 determines that the other voltage value is abnormal.

Description

  The present invention relates to a stroke sensor, an actuator including the same, and a rear wheel steering apparatus.

  Conventionally, for the purpose of improving turning performance and the like, a four-wheel steering (4WS) vehicle has been proposed in which the rear wheels are steered in response to steering of the front wheels by a driver's steering operation. The rear wheel steering device mounted on such a four-wheel steering vehicle includes a rear wheel steering shaft that steers the rear wheel by moving in the axial direction, and a steering shaft drive device that moves the rear wheel steering shaft in the axial direction. What you have is known. Some rear wheel steering devices are provided with a lock device that restricts the axial movement of the rear wheel steering shaft at the neutral position of the rear wheel steering angle. Is prevented.

  For example, Patent Document 1 includes a lock pin that can be moved (stroked) in a direction of moving toward and away from the rear wheel turning shaft, and the lock pin is engaged with a groove (concave portion) formed in the rear wheel turning shaft. Thus, a lock device that restricts the axial movement of the rear wheel steering shaft is disclosed. Further, this lock device is provided with a stroke sensor using a variable resistor, and detects the position (stroke position) of the lock pin (see Patent Document 1, FIG. 3). Specifically, in this stroke sensor, a protrusion that contacts the resistor is provided so as to be able to move together with the lock pin, and the stroke position of the lock pin is detected based on the voltage value at the contact portion. Accordingly, for example, the rear wheel turning shaft is prevented from moving in the axial direction in a state where the lock pin is not completely detached from the groove portion.

Japanese Utility Model Publication No. 61-66066

  However, in the stroke sensor as described in Patent Document 1, for example, when the protrusion is short-circuited to the power supply terminal, the detected voltage value does not change even if the lock pin reciprocates. It will remain. In such a case, since there is a lock pin at a stroke position corresponding to a constant voltage value, detection is continued, so the detected stroke position may differ greatly from the actual stroke position. . As a result, for example, there is a risk of erroneous determination that the lock pin is disengaged even though the lock pin is engaged with the groove, and there is still room for improvement in this respect.

  The present invention has been made in order to solve the above-described problems, and an object of the present invention is to provide a stroke sensor capable of suppressing a significant difference between a detected stroke position and an actual stroke position, an actuator including the same, and a rear The object is to provide a wheel steering device.

  A stroke sensor that solves the above-mentioned problem is a sensor that detects a stroke position of a detection object that reciprocates, and is connected to a first and second resistors connected to a terminal that becomes a first potential, and a terminal that becomes a second potential. Third and fourth resistors, a first contact body that contacts the first resistor and the third resistor body, a second contact body that contacts the second resistor body and the fourth resistor body, A detection circuit that detects a stroke position of the detection target based on at least one of a voltage value of the first contact body and a voltage value of the second contact body, The relative position of the resistors and the relative position of the contacts are held so as not to change due to the movement of the detection target, and either one of the contacts or the resistors is Accompanying the detection target And the other is provided on a fixed member whose position is not changed by the reciprocation of the detection target, and the detection unit is one of the voltage values generated in the first and second contact bodies. If the other voltage value does not change even if the other voltage value changes, the gist is to determine that the other voltage value is abnormal.

  According to the above configuration, since the resistance value of each resistor of the bridge circuit changes according to the stroke position of the detection target, the stroke position of the detection target is based on at least one of the voltage values of the first and second contact bodies. Can be detected. Moreover, since the relative position of each resistor and the relative position of each contact body are hold | maintained so that it may not change with the movement of each detection object, respectively, if abnormality, such as a short circuit, has not occurred, the 1st contact As the voltage value generated in the body changes, the voltage value generated in the second contact body also changes. Therefore, if one of the voltage values generated in the first and second contact bodies changes, but the other voltage value does not change, it can be determined that the other voltage value is abnormal. . Thereby, it can prevent detecting a stroke position based on an abnormal voltage value, and can control that a detected stroke position and an actual stroke position differ greatly.

  The gist of an actuator for solving the above problems is that it includes a movable member that reciprocates, a drive unit that moves the movable member, and a stroke sensor configured as described above that detects a stroke position of the movable member.

According to the above configuration, since it is possible to prevent the movable member from reciprocating based on a stroke position that is significantly different from the actual stroke position, it is possible to improve its reliability.
A rear wheel steering device that solves the above problems includes a rear wheel steering shaft that steers a rear wheel by moving in the axial direction, a steering shaft drive device that axially moves the rear wheel steering shaft, and the rear wheel steering. A locking member having an engaging convex portion engageable with an engaging concave portion formed on the rear wheel turning shaft, wherein the locking device is capable of restricting axial movement of the shaft. And an actuator having the above-described configuration that reciprocates the lock member to engage and disengage the engaging convex portion with the concave portion.

  According to the above configuration, since it is possible to prevent the operation of the steered shaft drive device from being controlled based on a stroke position that is significantly different from the actual stroke position, for example, a state in which the engagement convex portion is engaged with the engagement concave portion Thus, it is possible to more reliably prevent the rear wheel turning shaft from moving in the axial direction.

  According to the present invention, it is possible to suppress a significant difference between the detected stroke position and the actual stroke position.

The schematic block diagram of a four-wheel steering vehicle. Sectional drawing of the locking device vicinity. The expanded sectional view which shows schematic structure of the stroke sensor vicinity. The circuit diagram of a stroke sensor.

Hereinafter, an embodiment of a stroke sensor, an actuator including the same, and a rear wheel steering device will be described with reference to the drawings.
As shown in FIG. 1, the vehicle 1 is equipped with a front wheel steering device 3 that steers the front wheels 2F and a rear wheel steering device 4 that steers the rear wheels 2R. That is, the vehicle 1 is configured as a four-wheel steering (4WS) vehicle that steers the rear wheels 2R in response to the steering of the front wheels 2F by the driver's steering operation, and the turning performance thereof is improved. ing.

First, the mechanical configuration of the front wheel steering device will be described.
The front wheel steering device 3 includes a steering shaft 12 to which the steering wheel 11 is fixed, and a front wheel turning shaft (rack shaft) 13 that changes the turning angle of the front wheel 2F by moving in the axial direction according to the rotation of the steering shaft 12. And. The steering shaft 12 is formed by connecting a column shaft 14, an intermediate shaft 15, and a pinion shaft 16 in this order from the steering wheel 11 side. Further, the front wheel steering device 3 includes a substantially cylindrical front wheel side housing 17 into which the front wheel steering shaft 13 is inserted so as to be able to reciprocate.

  Specifically, the front wheel turning shaft 13 and the pinion shaft 16 are disposed in the front wheel side housing 17 with a predetermined crossing angle, and are formed on the rack teeth 13 a and the pinion shaft 16 formed on the front wheel turning shaft 13. The rack and pinion mechanism 21 is configured by meshing with the pinion teeth 16a. In addition, a tie rod 23 is rotatably connected to both ends of the front wheel steering shaft 13 via a ball joint 22 provided at the shaft end. And the front-end | tip of the tie rod 23 is connected with the knuckle which is not illustrated to which the front wheel 2F was assembled | attached. Therefore, in the front wheel steering device 3, the rotation of the steering shaft 12 accompanying the steering operation is converted into the axial movement of the front wheel turning shaft 13 by the rack and pinion mechanism 21, and this axial movement is transmitted to the knuckle via the tie rod 23. By doing so, the turning angle of the front wheel 2F is changed.

  The front wheel steering device 3 is configured as a so-called column assist type electric power steering device that rotationally drives the column shaft 14 using the assist motor 25 as a drive source. Specifically, the assist motor 25 is drivingly connected to the column shaft 14 via a speed reduction mechanism 26 formed of a worm and wheel or the like. The rotation of the assist motor 25 is decelerated by the speed reduction mechanism 26 and transmitted to the column shaft 14 so that the motor torque is applied to the steering shaft 12 as an assist force.

Next, the mechanical configuration of the rear wheel steering device will be described.
The rear wheel steering device 4 moves in the axial direction to change the turning angle of the rear wheel 2R, and a rear wheel turning shaft (rack shaft) 31 and a turning shaft drive device 32 that moves the rear wheel turning shaft 31 in the axial direction. And. The rear wheel steering device 4 includes a substantially cylindrical rear wheel side housing 33 into which the rear wheel turning shaft 31 is inserted so as to be reciprocally movable.

  Specifically, the steered shaft drive device 32 includes a steered motor 34 serving as a drive source thereof, and a pinion shaft 36 that is drivingly coupled to the steered motor 34 via a speed reduction mechanism 35 such as a worm and wheel. . In addition, the brushless motor is employ | adopted for the steering motor 34 of this embodiment. The rear wheel turning shaft 31 and the pinion shaft 36 are arranged in the rear wheel side housing 33 with a predetermined crossing angle, and rack teeth 31 a formed on the rear wheel turning shaft 31 and a pinion formed on the pinion shaft 36. A rack and pinion mechanism 37 is configured by meshing with the teeth 36a. In addition, tie rods 39 are rotatably connected to both ends of the rear wheel turning shaft 31 via ball joints 38 provided at the shaft end portions. The tip of the tie rod 39 is connected to a knuckle (not shown) to which the rear wheel 2R is assembled. Therefore, in the rear wheel steering device 4, the rotation of the pinion shaft 36 accompanying the driving of the steered shaft drive device 32 is converted into the axial movement of the rear wheel steered shaft 31 by the rack and pinion mechanism 37, and this axial movement is tie rod. By being transmitted to the knuckle via 39, the turning angle of the rear wheel 2R is changed.

Further, the rear wheel steering device 4 includes a lock device 41 that restricts the axial movement of the rear wheel steering shaft 31 at the neutral position of the steering angle of the rear wheel 2R (the steering angle at which the vehicle 1 goes straight).
As shown in FIG. 2, the lock device 41 includes a lock housing 42 that is fixed to the rear wheel side housing 33 in a manner protruding in a direction orthogonal to the axial direction of the rear wheel steering shaft 31. The lock housing 42 includes a bottomed cylindrical solenoid housing portion 44 in which the solenoid 43 is housed, and a bottomed cylindrical biasing member housing portion that protrudes from the bottom portion of the solenoid housing portion 44 to the side opposite to the rear wheel steering shaft 31. 45. On the other hand, the rear wheel side housing 33 is formed with a through hole 46 penetrating the inner and outer periphery thereof. The opening end of the solenoid housing portion 44 is fixed to the rear wheel side housing 33 so that the lock housing 42 is arranged coaxially with the through hole 46.

  The solenoid 43 includes an annular fixed iron core 51 and a solenoid coil 52 that are fixed in the solenoid housing portion 44, and a columnar movable iron core 53 that is housed on the inner peripheral side of the fixed iron core 51 and the solenoid coil 52. ing. A cylindrical engagement convex portion 54 that is inserted into the rear wheel side housing 33 through the through hole 46 is formed at the end of the movable iron core 53 on the rear wheel turning shaft 31 side. On the other hand, an engagement recess 55 into which the engagement protrusion 54 can be inserted is formed on the outer peripheral surface of the rear wheel steering shaft 31. The movable iron core 53 includes a lock position (a position of the movable iron core 53 indicated by a solid line in FIG. 2) where the engaging convex portion 54 engages with the engaging concave portion 55, and the engaging convex portion 54 from the engaging concave portion 55. It is in contact with and away from the unlocking position (the position of the movable iron core 53 indicated by a two-dot chain line in FIG. 2) perpendicular to the axis of the rear wheel turning shaft 31, that is, the rear wheel turning shaft 31. Reciprocating motion (stroke) is possible in the direction (stroke direction). A bush (sliding bearing) 56 is provided on the inner peripheral surface of the through hole 46 to support the engaging convex portion 54 so as to reciprocate in the stroke direction.

  The movable iron core 53 is formed with a columnar extension 57 that protrudes on the opposite side of the rear wheel turning shaft 31 and that is partially housed in the biasing member housing 45. A bottomed cylindrical receiving member 60 having a flange portion 59 is fixed to the distal end of the extending portion 57. A support member 61 such as a snap ring is fixed to the inner peripheral surface of the urging member accommodating portion 45. In the urging member housing 45, the stroke positions of the urging member 62 such as a coil spring and the movable iron core 53 arranged in a compressed state from the natural length between the support member 61 and the receiving member 60 are arranged. A stroke sensor 63 for detection is accommodated. From the stroke sensor 63, output signals S1, S2 corresponding to the stroke position of the movable iron core 53 are output to the ECU 71 as will be described later.

  Therefore, in the lock device 41, the movable iron core 53 is moved to the lock position by the urging force of the urging member 62, and the engagement convex portion 54 is engaged with the engagement concave portion 55, whereby the axial direction of the rear wheel steering shaft 31 is achieved. Movement is restricted. On the other hand, when the solenoid coil 52 is energized, the movable iron core 53 is attracted to the fixed iron core 51 and moved to the unlock position, and the engaging convex portion 54 is disengaged from the engaging concave portion 55, whereby the rear wheel turning shaft 31. The restriction on the movement in the axial direction is released. That is, in this embodiment, the movable iron core 53 functions as a detection target, a movable member, and a lock member, the fixed iron core 51 and the solenoid coil 52 function as a drive unit, and the solenoid 43 functions as an actuator. The lock housing 42 functions as a fixed member whose position does not change with the reciprocation of the movable iron core 53.

Next, the electrical configuration of the rear wheel steering device will be described.
As shown in FIG. 1, the rear wheel steering device 4 includes an ECU 71 that controls the operation of the steered shaft drive device 32 and the lock device 41. The ECU 71 includes a vehicle speed sensor 72 that detects the vehicle speed SPD of the vehicle 1, a steering sensor 73 that detects the steering angle θs of the steering wheel 11, and a rotation angle sensor 74 that detects the rotation angle θm of the steering motor 34 (rotor). It is connected. The ECU 71 is connected to a stroke sensor 63 of the lock device 41, and output signals S <b> 1 and S <b> 2 are input from the stroke sensor 63. The ECU 71 continuously detects the stroke position of the movable iron core 53 between the lock position and the unlock position based on the output signals S1 and S2, as will be described later. That is, in the present embodiment, the ECU 71 functions as a detection unit. The ECU 71 controls the operation of the steered shaft drive device 32 and the lock device 41 based on these state quantities.

  More specifically, the ECU 71 steers the rear wheels 2R in response to the steering of the front wheels 2F when the vehicle speed SPD is traveling at a low speed less than a predetermined vehicle speed (for example, when entering a garage). When the vehicle is traveling at medium to high speed, the turning angle of the rear wheel 2R is held at the neutral position.

  Specifically, when the ECU 71 determines that the vehicle speed SPD is less than the predetermined vehicle speed and the movable iron core 53 is in the unlock position, the ECU 71 calculates the target turning angle of the rear wheel 2R according to the steering angle θs. Then, the operation of the steering motor 34 is controlled so that the actual turning angle of the rear wheel 2R becomes the target turning angle. Note that the ECU 71 of the present embodiment also detects the rotation angle θm of the steered motor 34 as an absolute angle based on the rotation angle θm when the steered angle of the rear wheel 2R is in the neutral position, in addition to the electrical angle. The actual turning angle of the rear wheel 2R is estimated based on the rotation angle θm detected by the absolute angle. When the ECU 71 determines that the movable iron core 53 is in the locked position, the ECU 71 controls the operation of the solenoid 43 so that the movable iron core 53 moves to the unlocked position. The steering motor 34 is driven after the restriction on the axial movement is released.

  On the other hand, when the vehicle speed SPD is equal to or higher than the predetermined vehicle speed and the turning angle of the rear wheel 2R is not in the neutral position, the ECU 71 operates the steering motor 34 so that the turning angle of the rear wheel 2R becomes the neutral position. To control. When the ECU 71 determines that the turning angle of the rear wheel 2R has reached the neutral position, the ECU 71 controls the operation of the solenoid 43 so that the movable iron core 53 moves to the lock position, and the lock device 41 controls the axis of the rear wheel turning shaft 31. The direction movement is restricted and the turning angle of the rear wheel 2R is held at the neutral position.

Next, detection of the stroke position of the movable iron core by the stroke sensor will be described.
As shown in FIGS. 2 and 3, the stroke sensor 63 includes first and second resistors 81 and 82 and a common resistor 83.

  Specifically, the first and second resistors 81 and 82 and the common resistor 83 are made of the same metal material formed in a band shape, and are all arranged so as to be parallel to the stroke direction of the movable iron core 53. ing. The length in the longitudinal direction (stroke direction) and the length in the short direction of the first resistor 81 are set substantially equal to the length in the longitudinal direction and the length in the short direction of the second resistor 82. And the second resistor 82 have substantially the same shape. The length in the longitudinal direction of the common resistor 83 is set to be longer than the length in the longitudinal direction of the first resistor 81 and the second resistor 82, and the length in the short direction of the common resistor 83 is The length of the first and second resistors 81 and 82 is set to be approximately equal to the short direction length. The first resistor 81 and the second resistor 82 are arranged with an interval in the stroke direction, and the common resistor 83 is a rear wheel turning shaft between the first and second resistors 81 and 82. They are juxtaposed at intervals along the axial direction of 31. The first and second resistors 81 and 82 and the common resistor 83 are fixed in a state where insulation is ensured in the biasing member accommodating portion 45 of the lock housing 42, respectively. Accordingly, the relative positions of the first and second resistors 81 and 82 and the common resistor 83 are held so as not to change due to the movement of the movable iron core 53.

  As shown in FIG. 3, the connection end 81 a of the first resistor 81 on the side opposite to the rear wheel turning shaft 31 is connected to a ground terminal 86 extending from the ground via a wiring 85. Further, the connection end portion 82 a on the rear wheel turning shaft 31 side in the second resistor 82 is connected to a ground terminal 88 extending from the ground via a wiring 87. That is, the ground potential corresponds to the first potential, and the ground terminals 86 and 88 correspond to the terminals that become the first potential. A central portion 83 a in the longitudinal direction of the common resistor 83 is connected to a power supply terminal 90 provided in the ECU 71 via a wiring 89. A high potential (for example, 5 V) as a second potential is applied to the power supply terminal 90 via an internal circuit of the ECU 71. That is, the power supply terminal 90 corresponds to a terminal having a second potential, and contacts the first contact body 91 across the longitudinal central portion 83a connected to the terminal having the second potential in the common resistor 83. The side in contact with the third resistor and the second contact body 92 corresponds to the fourth resistor.

  The stroke sensor 63 includes a first contact body 91 that contacts both the first resistor 81 and the third resistor portion of the common resistor 83, and a fourth resistor body of the second resistor 82 and the common resistor 83. A second contact body 92 that contacts both of the portions, and a connecting member 93 that is fixed to the extending portion 57 of the movable iron core 53 are provided.

  Specifically, the first and second contact bodies 91 and 92 are each made of the same metal material formed in a rectangular plate shape, and the connecting member 93 is made of an insulating material. And the 1st contact body 91 and the 2nd contact body 92 are being fixed to the connection member 93 at predetermined intervals in the stroke direction. Thereby, the relative positions of the first and second contact bodies 91 and 92 are held so as not to change due to the movement of the movable iron core 53, and the first and second contact bodies 91 and 92 are relative to each other in the stroke direction. In a state where the position is maintained and insulation is ensured, the movable core 53 accompanies the detection target and reciprocates. The predetermined interval is such that the length L1 between the contact portion of the first resistor 81 with the first contact body 91 and the connection end 81a is the second contact body in the fourth resistor portion of the common resistor 83. 92 is equal to the length L4 of the fourth resistor formed between the contact portion with the longitudinal center portion 83a and the contact portion with the second contact body 92 and the connection end portion of the second resistor 82. The length L2 between the first resistor 82a and the second resistor portion of the common resistor 83 is the length of the third resistor formed between the contact portion with the first contact body 91 and the central portion 83a in the longitudinal direction. The interval is set to be equal to L3. The first contact body 91 and the second contact body 92 are connected to the ECU 71, respectively. The ECU 71 includes an output signal S1 indicating a voltage value V1 generated in the first contact body 91, and the second contact body. An output signal S2 indicating a voltage value V2 generated at 92 is input. The ECU 71 acquires the voltage values V1 and V2 from the output signals S1 and S2 at every predetermined sampling period.

  Therefore, as shown in FIG. 4, a pair of resistors R1 and R3 connected in series by the first and second resistors 81 and 82, the common resistor 83, and the first and second contacts 91 and 92 are connected in series. A bridge circuit is formed by connecting a pair of resistors R2 and R4 connected to each other in parallel. The resistance value of the resistor R1 changes according to the length L1 on the first resistor 81, the resistance value of the resistor R2 changes according to the length L2 on the second resistor 82, and the resistance value of the resistor R3. Changes according to the length L3 on the common resistor 83, and the resistance value of the resistor R4 changes according to the length L4 on the common resistor 83. Since the lengths L1 to L4 change according to the positions of the first and second contact bodies 91 and 92, that is, the stroke positions of the movable iron core 53, the resistance values of the resistors R1 to R4 are the movable iron core 53. It changes according to the stroke position. Specifically, the resistance values of the resistor R1 and the resistor R4 are the largest when the movable iron core 53 is in the locked position, and become smaller toward the unlocked position. On the other hand, the resistance values of the resistor R2 and the resistor R3 are the smallest when the movable iron core 53 is in the locked position, and increase as it goes toward the unlocked position. Since the length L1 and the length L4 are equal to each other as described above, the resistance value of the resistor R1 and the resistance value of the resistor R4 are equal to each other, and the length L2 and the length L3 are equal to each other. The resistance value of the resistor R2 and the resistance value of the resistor R3 are equal to each other. The voltage value V1 of the first contact body 91 is expressed by the following formula (1), and the voltage value V2 of the second contact body 92 is expressed by the following formula (2).

V1 = R1 · V0 / (R1 + R3) (1)
V2 = R2 / V0 / (R2 + R4) = R2 / V0 / (R1 + R3) (2)
“V0” indicates a voltage value at the power supply terminal 90 of the ECU 71. In addition, since the first contact body 91 and the second contact body 92 are connected so as to maintain an interval in the stroke direction, the sum of the resistance value of the resistor R1 and the resistance value of the resistor R3 (the resistance R2 The sum of the resistance value and the resistance value of the resistor R4) is constant.

  Therefore, the voltage value V1 of the first contact body 91 gradually decreases as the movable core 53 moves from the locked position to the unlocked position, whereas the voltage value V2 of the second contact body 92 is locked by the movable core 53. It gradually increases from the position toward the unlock position. As a result, the voltage ratio (V1 / V2) α gradually decreases as the movable iron core 53 moves from the locked position to the unlocked position. Then, based on the fact that the voltage ratio α gradually decreases from the locked position toward the unlocked position in this way, the ECU 71 determines the stroke position of the movable iron core 53 from the locked position based on the magnitude of the voltage ratio α. Detect continuously between lock positions. In the ECU 71 of the present embodiment, the movable iron core 53 is in the locked position when the voltage ratio α is greater than or equal to a predetermined threshold value, and the movable iron core 53 is unlocked when the voltage ratio α is less than the predetermined threshold value. Determined to be in position.

  Furthermore, when the voltage value of one of the voltage values V1 and V2 changes, the ECU 71 of the present embodiment fixes the other voltage value due to a short circuit or the like. It is determined that an abnormality has occurred. The ECU 71 is provided with a memory 94. The ECU 71 determines whether or not the voltage value has changed by comparing the previous voltage values V1 and V2 stored in the memory 94 with the latest voltage values V1 and V2. judge. When the ECU 71 detects an abnormality in the voltage value, the ECU 71 stops detecting the stroke position based on the voltage ratio α (the voltage value determined to be abnormal), and based on the voltage value with no abnormality. While detecting the stroke position, the driver is notified of the occurrence of an abnormality by notifying means (not shown) such as a warning lamp.

Next, the effect of this embodiment will be described.
(1) When the voltage value of one of the voltage values V1 and V2 generated in the first and second contact bodies 91 and 92 changes, but the other voltage value does not change, the ECU 71 Is detected as abnormal, the detection of the stroke position based on the abnormal voltage value is stopped, and the stroke position is detected based on the abnormal voltage value. It can be suppressed that the actual stroke position differs greatly.

  (2) Since it is possible to prevent the operation of the steered shaft drive device 32 from being controlled based on a stroke position that is greatly different from the actual stroke position, for example, a state in which the engagement convex portion 54 is engaged with the engagement concave portion 55 That is, it is possible to prevent the rear wheel steering shaft 31 from moving in the axial direction in a state where the movable iron core 53 is in the locked position.

In addition, the said embodiment can also be implemented in the following aspects which changed this suitably.
In the above embodiment, the length L1 on the first resistor 81 and the length L4 on the common resistor 83 are different, and the length L2 on the second resistor 82 and the length on the common resistor 83 are different. You may fix the 1st and 2nd contact bodies 91 and 92 to the connection member 93 so that L3 may differ. That is, the resistance value of the resistor R1 and the resistance value of the resistor R4, and the resistance value of the resistor R2 and the resistance value of the resistor R3 may be different from each other.

  In the above embodiment, the first potential is the ground potential. However, the present invention is not limited to this, and the first potential may be lower or higher than the potential of the power supply terminal 90 of the ECU 71 (second potential). In this case, “V0” in the equations (1) and (2) is a potential difference between the first potential and the second potential.

  In the above embodiment, the ECU 71 detects the stroke position based on the voltage ratio α when there is no abnormality in the voltage value. However, the present invention is not limited to this. For example, the ECU 71 detects the difference between the voltage value V1 and the voltage value V2. Based on this, the stroke position may be detected.

  In the above embodiment, when the voltage value of one of the voltage values V1 and V2 has changed but the other voltage value has not changed, the other voltage value is abnormal. For example, other conditions may be added when the abnormality determination of the voltage value is performed.

  In the above embodiment, the ECU 71 detects an abnormality in the stroke position and the voltage value based on the output signals S1 and S2. However, the present invention is not limited to this, and a control circuit that detects the abnormality in the stroke position and the voltage value is separate from the ECU 71. An output signal indicating the stroke position may be output from the stroke sensor 63 to the ECU 71.

  In the above-described embodiment, the first and second contact bodies 91 and 92 are fixed to the lock housing 42, and the first and second resistor bodies 81 and 82 and the common resistor body 83 are maintained at the relative positions in the stroke direction. It may be provided so as to be able to reciprocate along with the movable iron core 53 in a state.

  In the above embodiment, the movable iron core 53 as the movable member is reciprocated by the electromagnetic force generated by energizing the solenoid coil 52. However, the present invention is not limited to this. For example, the movable iron core 53 is reciprocated using hydraulic pressure or the like. Also good.

  In the above embodiment, the solenoid 43 as an actuator is used as a drive source of the lock device 41 of the rear wheel steering device 4, but is not limited thereto, and may be used as a drive source of other devices such as an electromagnetic valve. . Even if comprised in this way, since it can prevent reciprocating the movable iron core 53 based on the stroke position largely different from an actual stroke position, the reliability can be improved.

  In the above embodiment, the stroke sensor 63 is used to detect the stroke position of the movable iron core 53. However, the present invention is not limited to this, and may be used to detect the stroke position of another reciprocating member.

  DESCRIPTION OF SYMBOLS 1 ... Vehicle, 2F ... Front wheel, 2R ... Rear wheel, 3 ... Front wheel steering device, 4 ... Rear wheel steering device, 31 ... Rear-wheel steering shaft, 32 ... Steering shaft drive device, 41 ... Lock device, 43 ... Solenoid, DESCRIPTION OF SYMBOLS 51 ... Fixed iron core, 52 ... Solenoid coil, 53 ... Movable iron core, 54 ... Engagement convex part, 55 ... Engagement recessed part, 63 ... Stroke sensor, 71 ... ECU, 81 ... 1st resistor, 82 ... 2nd resistor , 83: Common resistor, 86, 88 ... Ground terminal, 90 ... Power supply terminal, 91 ... First contact body, 92 ... Second contact body, 93 ... Connecting member, V1, V2 ... Voltage value.

Claims (3)

In the stroke sensor that detects the stroke position of the detection target that reciprocates,
A first resistor and a second resistor connected to a terminal having a first potential; a third and a fourth resistor connected to a terminal having a second potential; and the first resistor and the third resistor. A bridge circuit configured to include a first contact body in contact with the second contact body and the second contact body in contact with the second resistor and the fourth resistor;
A detection unit that detects a stroke position of the detection target based on at least one of a voltage value of the first contact body and a voltage value of the second contact body;
The relative positions of the resistors and the relative positions of the contacts are held so as not to change due to the movement of the detection target,
Either one of the contact bodies and each resistor is provided to be able to reciprocate along with the detection target, and the other is provided to a fixing member whose position does not change due to the reciprocation of the detection target.
When the voltage value of one of the voltage values generated in the first and second contact bodies changes but the other voltage value does not change, the detection unit detects that the other voltage value is abnormal. It is determined that there is a stroke sensor.   An actuator comprising: a movable member that reciprocates; a drive unit that moves the movable member; and a stroke sensor according to claim 1 that detects a stroke position of the movable member. A rear wheel turning shaft for turning the rear wheel by moving in the axial direction, a turning shaft drive device for moving the rear wheel turning shaft in the axial direction, and a lock device capable of regulating axial movement of the rear wheel turning shaft And a rear wheel steering device comprising:
The locking device includes a locking member having an engaging convex portion that can be engaged with an engaging concave portion formed on the rear wheel steering shaft, and reciprocating the locking member to engage the engaging convex portion with the concave portion. A rear wheel steering apparatus comprising the actuator according to claim 2 to be detached.